The opium or oil poppy, Papaver somniferum, is an erect annual plant which is cropped in order to produce alkaloids such as morphine, thebaine, oripavine, codeine, pseudomorphine and the like. Alkaloids are extracted from the poppy capsules of Papaver somniferum by two commercial methods. In one method, the immature capsule is cut and the latex collected from the wound. The air-dried latex is opium which contains alkaloids.
In a second method, the mature poppy capsules and the poppy capsule stems are collected, and threshed to remove the seeds and form a straw. When necessary, the straw is dried to a water content below 16%. Extraction by solvent or water or super critical fluid, such as CO2, is usually employed to remove the alkaloids from the straw to produce a “concentrate of poppy straw”.
While thebaine has no direct medical use, during recent years, demand for this alkaloid has increased as it is the raw material for the production of semi-synthetic drugs having analgesic, antitussive and sedative properties. Hydrocodone, thebacon, oxycodone and drotebanolare are other useful drugs that may be derived from thebaine. Naloxone made from thebaine is used as an antagonist in the treatment of morphine and heroin addicts. Etorphine and some of its analogues known as Bentley compounds prepared from thebaine have a much greater activity than morphine and are used in veterinary medicine and in capturing wild animals. The Diels-Adler adducts of thebaine are easily prepared in high yields and are of great interest.
The availability of thebaine is limited and its cost high. One reason for the limited availability of thebaine, and its high cost, is that total synthesis is difficult. Yet, the demand for thebaine remains. A second reason for the limited availability of thebaine, and its high cost, is that the primary source of thebaine is by extraction from the poppy plant, Papaver somniferum. 
Morphine, is the major alkaloid that accumulates in capsules of Papaver somniferum. Moreover, according to the Merck Index, 11th edition, air dried latex contains alkaloids in the amounts shown in Table I.
TABLE Iopiumstrawmorphine, %10-161-3codeine, %0.8-2.50.05-0.3 oripavine, %  0-0.1  0-0.05thebaine, %0.5-2  0.15-0.65
As can be seen, from the above table the yield of thebaine and oripavine is confounded with that of other alkaloids. Thus, the supply of thebaine and oripavine is to a great degree limited to some fraction of the demand for morphine.
As seen from Table I oripavine is not recoverable from Papaver somiferum in any practical yield. Since oripavine has traditionally not been demanded in the same quantities as thebaine, there has been no real shortage of this material. However Papaver somniferum is now being increasingly cultivated for the production of oripavine for the pharmaceutical market.
Traditionally, trinexapac-ethyl, an acylcyclohexanedione compound has been used as a plant growth regulator, which reduces stem growth by inhibition of internode elongation. It is absorbed by the foliage with translocation to the growing shoot. Used commonly on highly maintained turfgrasses, it has had a role in evaluating growth suppression patterns and suppression of seedhead formation. Further uses of trinexapac-ethyl include the prevention of lodging in cereals, on winter oilseed rape and as a maturation promoter in sugar cane. Prohexadione-calcium is the calcium salt of another acylcyclohexanedione compound and is a plant growth regulator and retardant and, like trinexapac-ethyl, has also been used as an anti-lodging agent in small grain cereals. It could also be used as a growth retardant in turf, peanuts, flowers and to inhibit new twig elongation of fruit trees.
In work leading up to the present invention, the inventors unexpectedly found that the application of certain plant growth regulators, such as acylcyclohexanedione compounds and methyl jasmonate, in combination or individually, to poppy plants altered the alkaloid composition of a poppy plant, in particular by decreasing the proportion of morphine and increasing the proportion of thebaine and oripavine in poppy plants when compared to control plants to which the plant growth regulators had not been applied.